We are interested in the synthesis and chemistry of new multifunctional compounds that contain the thiol ester group together with other reactive alkylating functions such as the aziridine, azirine, epoxide or episulfide rings, the bis (2- chloroethyl) amino, diazo or sulfonate groups or the alpha-methylene- gamma-thiobutyrolactone ring system. We also plan to develop novel, general synthetic procedures which will allow us to introduce the labile thiol ester group into complex molecules including certain nucleic acids, prostaglandins, steroid hormones and antibiotics. Several factors have raised our interest in the potential antineoplastic properties of multifunctional thiol esters. The thiol ester groups is a labile acylating function that reacts readily with amine and mercaptan groups in proteins or nucleic acids. The reactivity of the thiol ester group will be still greater in vivo as a result of metabolic activation by conversion to alpha-carbonyl sulfoxides using liver microsomal mixed function oxidases or related enzyme systems in other tissues. Multifunctional thiol esters will be prepared using the following methods: (1) Selective, mild procedures will be sought to permit facile conversion of carboxylic acids to thiol esters without the involvement of a labile acid halide intermediate or the free mercaptan nucleophile characteristic of the commonly used Schotten Baumann process. (2) New condensation and alkylation procedures will be developed to prepare thiol esters from aldehydes, ketones, tosylates, alkyl halides and other functional groups found in complex molecules. (3) The 1,3-oxathiolane ring system will be utilized in a novel general procedure to convert aldehydes, olefins, activated aromatic systems and other groups into thiol ester derivatives.